Selecting I/O Units

Selecting and communicating with I/O units. The I/O unit physical layer interface. Understanding the wide perspective.
Putting It Together

Now that I've introduced the terminology and discussed features important to selecting an I/O system, let's briefly summarize how to put it all together. The following outline describes how I approach the selection and implementation of I/O systems. I've found that these steps may occur in parallel and may be iterative in nature, with decisions being refined and becoming more accurate with each pass. Designing the system requires a significant amount of patience and persistence as well as a flair for precise detail.

  • Inventory the sensors and effectors the system specification requires. Include location, function and details of the devices. Spreadsheets are excellent tools for this documentation.

  • Determine accuracy and resolution requirements. Determine data rate and response-time requirements.

  • Estimate the expanse of the system. Chart the potential communication paths; require blueprints if necessary.

  • Evaluate I/O unit options to fulfill the points, expanse and throughput requirements.

  • Consider modularity not only as a flexible means of communication but also as a means of simplifying maintenance over the system's lifetime.

  • Select the communication infrastructure. Refine the system expanse and the communication paths.

  • Evaluate software support for each I/O unit considered for the system.

  • Start wiring!

Bryce Nakatani ( is an engineer at Opto 22, a manufacturer of automation components in Temecula, California. He specializes in real-time controls, software design, analog and digital design, network architecture and instrumentation.


One Click, Universal Protection: Implementing Centralized Security Policies on Linux Systems

As Linux continues to play an ever increasing role in corporate data centers and institutions, ensuring the integrity and protection of these systems must be a priority. With 60% of the world's websites and an increasing share of organization's mission-critical workloads running on Linux, failing to stop malware and other advanced threats on Linux can increasingly impact an organization's reputation and bottom line.

Learn More

Sponsored by Bit9

Linux Backup and Recovery Webinar

Most companies incorporate backup procedures for critical data, which can be restored quickly if a loss occurs. However, fewer companies are prepared for catastrophic system failures, in which they lose all data, the entire operating system, applications, settings, patches and more, reducing their system(s) to “bare metal.” After all, before data can be restored to a system, there must be a system to restore it to.

In this one hour webinar, learn how to enhance your existing backup strategies for better disaster recovery preparedness using Storix System Backup Administrator (SBAdmin), a highly flexible bare-metal recovery solution for UNIX and Linux systems.

Learn More

Sponsored by Storix